1. Technical Field
The present invention relates to a target deriving process.
2. Related Art
A radar device transmits transmission waves based on a transmission signal to the outside of a vehicle, and receives reflected waves from targets (for example, reflection points of preceding vehicles), and extracts frequency peaks. The frequency peaks are extracted from up sections in which the frequency of the transmission signal increases and down sections in which the frequency decreases, respectively.
The radar device calculates angle peaks which represent the angles of the targets with the frequency peaks of the individual sections, and associates the angle peaks of the individual sections with each other on the basis of a predetermined condition, thereby generating pair data items. The pair data items are data items including target information items of the targets. The target information items are information such as the longitudinal distances, transverse distances, and relative speeds of the targets as seen from the radar device. The longitudinal distances are the moving distances of the reflected waves from the positions of the targets to the radar device. The transverse distances are distances from the position of the radar device to the positions of the targets in the vehicle width direction of the vehicle.
On the basis of the target information items of the pair data items, the radar device determines whether pair data items generated at different process timings are pair data items of the same target. The different process timings are, for example, the timing of a previous target deriving process (hereinafter, referred to as the “previous process”) and the timing of a current target deriving process (hereinafter, referred to as the “current process”). The previous process and the current process are temporarily consecutive processes. As described above, the radar device determines whether pair data items generated at the different process timings are pair data items of the same target, other words, the radar device determines whether a pair data item of the previous process and a pair data item of the current process are temporarily consecutive pair data items. Thereafter, the radar device outputs target information items of pair data items having continuity a predetermined number of times in a plurality of processes, to a vehicle control device. Also, as a reference material describing a technology related to the present invention, there is Patent Literature 1 (JP-A-2003-149337).